Wheels and weed whackers

Perhaps you’ve seen this image before: a young kid tooling around on a pair of inline skates, pushed forward by a weed whacker cycle. While the instructions for this device would seem fairly obvious (attach wheel to weed whacker) the writeup appears to be nonexistent. If you have any information, do let us know, but in the meantime, enjoy these other weed whacker powered projects.

For fun and practicality, we’ll start with this weed whacker bike. It uses an Echo SRM-210 trimmer motor. The pedals of the bike were replaced with a second sprocket driven by a chain attached to the motor. The bike reportedly does up to 25mph and 100mpg. The nice thing about the these motors is they work no matter what the orientation.

We found another bike assisted by a weed whacker motor, but instead of removing the pedals and powering the gears, this bike simply attaches a 31cc weed whacker with a model plane propeller. The propeller provides thrust, but don’t expect this design to work near as efficiently as the previous one.

If you think we’re cheating by talking about bikes where we should be discussing skates, slow down. Trust us, you’ll really wish you could slow down when you strap on these skates: they pack 25cc motors mounted on the back of the right skate, which achieves speeds of 20mph like the kid in the picture. These are made to order by a Chinese manufacturer, just don’t bother trying to buy a pair in the UK.

On the first image, that’s not a weed whacker; those engines turn FAST, way too fast for most work unless you gear them down. I once made an outboard motor out of one and burned out the engine even after cutting the (trolling motor) prop blades down to stubs. I’m guessing that the motive power there is the drive train for a rototiller, which would have both the gear-down and right-angle things going on.

harvie, there’s a small clutch in the engin (as the video mentions), and you can’t just mount it to the back wheel since the engine turns at too many RPMs and too little torque to be able to get going. you might be able to have a friction wheel mounted to the tire, but I still think it would spin too fast. That’s what the bike in the video had all the gearing for.

#10: no, you can’t. You’ll nedd some kind of gearing to convert the high RPM of the engine to reasonable RPMs for you drive weel (and in the process upconvert the torque of course). The guy in the video does this with the chain and the sprockets. 13:1 IIRC from the video.

I have seen a guy around town with a similar motor hooked to a small sized (mini bike maybe?) rubber tire propelling his bike.

He has it mounted ontop the front tire set back near the bars, the motor drives the smaller tire, which is contacting the front wheel of the bike near the top and by the rider. This in turn spins the front tire, making it a fornt drive gas powered bike.

Im not exactly sure what type of engine or the mounting or anything, but he can also make it free-riding again, by not having the drive wheel contact the bike tire (hinging device or something)

He crank starts it like a landmower and has the throttle linked up to a bike brake on the handle bar.

The turkey who turned a bicycle into a motorcycle, must get a thrill from antagonising the police or just isn’t thinking. In most if not all jurisdictions motor assisted bicycles are legal to operate on roadways. Jerks like him make it more difficult for those who do try to build and operated modified or home built vehicles within the law.